/*
 * Copyright 2002-2018 the original author or authors.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      https://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package org.springframework.web.reactive.socket.adapter;

import io.undertow.websockets.core.CloseMessage;
import io.undertow.websockets.core.WebSocketCallback;
import io.undertow.websockets.core.WebSocketChannel;
import io.undertow.websockets.core.WebSockets;
import org.springframework.core.io.buffer.DataBuffer;
import org.springframework.core.io.buffer.DataBufferFactory;
import org.springframework.core.io.buffer.DataBufferUtils;
import org.springframework.lang.Nullable;
import org.springframework.util.ObjectUtils;
import org.springframework.web.reactive.socket.CloseStatus;
import org.springframework.web.reactive.socket.HandshakeInfo;
import org.springframework.web.reactive.socket.WebSocketMessage;
import org.springframework.web.reactive.socket.WebSocketSession;
import reactor.core.publisher.Mono;
import reactor.core.publisher.MonoProcessor;

import java.io.IOException;
import java.nio.ByteBuffer;
import java.nio.charset.StandardCharsets;

/**
 * Spring {@link WebSocketSession} implementation that adapts to an Undertow
 * {@link io.undertow.websockets.core.WebSocketChannel}.
 *
 * @author Violeta Georgieva
 * @author Rossen Stoyanchev
 * @since 5.0
 */
public class UndertowWebSocketSession extends AbstractListenerWebSocketSession<WebSocketChannel> {

    public UndertowWebSocketSession(WebSocketChannel channel, HandshakeInfo info, DataBufferFactory factory) {
        this(channel, info, factory, null);
    }

    public UndertowWebSocketSession(WebSocketChannel channel, HandshakeInfo info,
                                    DataBufferFactory factory, @Nullable MonoProcessor<Void> completionMono) {

        super(channel, ObjectUtils.getIdentityHexString(channel), info, factory, completionMono);
        suspendReceiving();
    }


    @Override
    protected boolean canSuspendReceiving() {
        return true;
    }

    @Override
    protected void suspendReceiving() {
        getDelegate().suspendReceives();
    }

    @Override
    protected void resumeReceiving() {
        getDelegate().resumeReceives();
    }

    @Override
    protected boolean sendMessage(WebSocketMessage message) throws IOException {
        ByteBuffer buffer = message.getPayload().asByteBuffer();
        if (WebSocketMessage.Type.TEXT.equals(message.getType())) {
            getSendProcessor().setReadyToSend(false);
            String text = new String(buffer.array(), StandardCharsets.UTF_8);
            WebSockets.sendText(text, getDelegate(), new SendProcessorCallback(message.getPayload()));
        } else if (WebSocketMessage.Type.BINARY.equals(message.getType())) {
            getSendProcessor().setReadyToSend(false);
            WebSockets.sendBinary(buffer, getDelegate(), new SendProcessorCallback(message.getPayload()));
        } else if (WebSocketMessage.Type.PING.equals(message.getType())) {
            getSendProcessor().setReadyToSend(false);
            WebSockets.sendPing(buffer, getDelegate(), new SendProcessorCallback(message.getPayload()));
        } else if (WebSocketMessage.Type.PONG.equals(message.getType())) {
            getSendProcessor().setReadyToSend(false);
            WebSockets.sendPong(buffer, getDelegate(), new SendProcessorCallback(message.getPayload()));
        } else {
            throw new IllegalArgumentException("Unexpected message type: " + message.getType());
        }
        return true;
    }

    @Override
    public Mono<Void> close(CloseStatus status) {
        CloseMessage cm = new CloseMessage(status.getCode(), status.getReason());
        if (!getDelegate().isCloseFrameSent()) {
            WebSockets.sendClose(cm, getDelegate(), null);
        }
        return Mono.empty();
    }


    private final class SendProcessorCallback implements WebSocketCallback<Void> {

        private final DataBuffer payload;

        SendProcessorCallback(DataBuffer payload) {
            this.payload = payload;
        }

        @Override
        public void complete(WebSocketChannel channel, Void context) {
            DataBufferUtils.release(this.payload);
            getSendProcessor().setReadyToSend(true);
            getSendProcessor().onWritePossible();
        }

        @Override
        public void onError(WebSocketChannel channel, Void context, Throwable throwable) {
            DataBufferUtils.release(this.payload);
            getSendProcessor().cancel();
            getSendProcessor().onError(throwable);
        }
    }

}
